Anodic Copper Oxidation in Alkaline Mediums with α-Alanine and Asparagine Acid Additives

Abstract

It was investigated α-alanine and asparagine acid influence on copper anodic process kinetics in alkaline electrolytes. The experiments were carried out at two systems: I -0.01 M NaOH +X M α-Ala (X=10 -4 ÷10 -1 M) and II -0.01 M NaOH +X M Asp (X=10 -5 ÷10 -3 M). It was found out that α-alanine (from С Ala = 5×10 -3 М to 2×10 -2 М) and asparagine acid (from С Asp =1×10 -5 to 1×10 -3 М) stimulate anodic processes at passive region and cause of metal local activation. However except this general regularity, the individual singularity at both systems were found out: at the I system local activation develops under Е LA =0.10-0.20 V, at the II system two local activation potentials were identified Е 1 LA =0,23-0,34 V and Е 2 LA =0.70-0.85 V, which were divided by repassivation region.

Comparison of Copper Anodic Behavior under Joint Presence of α-Alanine or β-Alanine and Chloride Ions

“…The obtained results have shown that in both background solutions copper undergoes local activation (LA) [1,2]. Under this pits have the view of etch-pits of spherical shape form on metal surface and its number was few (2-3 at working surface 7.85×10 -5 m 2 ).…”

“…Under this pits have the view of etch-pits of spherical shape form on metal surface and its number was few (2-3 at working surface 7.85×10 -5 m 2 ). Earlier local depassivation process mechanism at chosen background electrolytes was examined in details at [1,2] and it was interpreted as a nucleophile substitution reaction of passivator particles by amino acid (AA) anions of dissociative type (S N1 ) [3]. Addition of small concentrations of NaCl (1×10 -7 -1×10 -4 M) stabilizes investigated systems.…”